1. Field of the Invention
The invention relates to a control apparatus and a control method for a vehicular drive apparatus that includes a driving power source that includes an engine and a motor, and a shift portion that transmits power output from the driving power source to a drive wheel. More specifically, the invention relates to a technology for controlling the start of an engine.
2. Description of the Related Art
A control apparatus for a vehicular drive apparatus is available. The vehicular drive apparatus includes a driving power source that includes an engine and a motor, and a shift portion that transmits power output from the driving power source to a drive wheel. The control apparatus executes an engine speed control that increases an engine speed to a predetermined engine speed (for example, a self-operating speed at which the engine is completely self-operating) or higher, and executes an engine torque generation control that generates engine torque by supplying fuel and igniting the fuel at the predetermined engine speed or higher.
In the control apparatus for the vehicular drive apparatus, for example, if an accelerator pedal is depressed when a vehicle is driven in a motor-driven mode using only the motor as the driving power source, the period during which the power-on downshift of the shift portion is performed overlaps the period during which the engine is started, in some cases. In the cases, a shift control and the engine start control need to be executed taking into account, for example, fluctuations of torque due to the start of the engine. Thus, these controls are made complicated. Therefore, shift shock and engine start shock may be increased.
Accordingly, Japanese Patent Application Publication No. 2004-208417 (JP-A-2004-208417) describes a technology in which, in the case where it is determined that the period during which the shift of the shift portion is performed overlaps the period during which the engine is started, a shift determination is canceled, that is, the shift is not performed until the process of starting the engine is completed. This suppresses an increase in the shift shock or the engine start shock.
Japanese Patent Application Publication No. 2006-213149 (JP-A-2006-213149) describes a control apparatus for a vehicular drive apparatus. The vehicular drive apparatus includes a differential portion and a stepped shift portion. The differential portion includes a first element connected to an engine, a second element connected to a first motor, and a third element connected to a transmitting member and a second motor. The differential portion distributes output from the engine to the first motor and the transmitting member. The stepped shift portion is provided in a power transmission path from the transmitting member to a drive wheel. The control apparatus increases an engine speed to a predetermined engine speed or higher by making the first motor function as the starter, and generates engine torque by supplying fuel and igniting the fuel at the predetermined engine speed or higher, and thus starts the engine.
In the control apparatus for the vehicular drive apparatus described in the publication No. 2006-213149, the reaction torque transmitted from the drive wheel and borne by the transmitting member is decreased during the shift of the shift portion. In other words, the reaction force for increasing the engine speed is decreased. Thus, in the case where the period during which the shift of the shift portion is performed overlaps the period during which the engine is started, the torque balance between elements of the differential portion needs to be maintained while controlling the engine speed to start the engine. This makes the controls more complicated. Thus, the shift shock or the engine start shock may be further increased.
Accordingly, the publication No. 2006-213149 describes a technology in which, in the case where it is determined that the period during which the shift of the shift portion is performed overlaps the period during which the engine is started, the engine start control is started after the shift of the shift portion is completed, or the shift control for the shift portion is started after the engine is started.
However, in the case where the engine start control is started after the shift of the shift portion is completed, or the shift control for the shift portion is started after the engine is started, the period from when a driver requests acceleration until when required driving power is output, that is, the period required to increase the torque (i.e., sum of the period required to perform the shift, and the period required to start the engine) is increased. This may deteriorate acceleration feeling. Thus, a technology for suppressing the shock due to the start of the engine, and quickly generating the engine torque has not been proposed.